The present invention relates generally to ink markers and more particularly to erasable ink markers.
Ink markers for making markings that are erasable from the surface of a substantially non-porous substrate using a dry eraser are well-known. For example, in U.S. Pat. No. 3,949,132, inventors Seregely et al., which issued Apr. 6, 1976, and which is incorporated herein by reference, there is disclosed an ink composition for writing instruments having a porous writing point which will write satisfactorily on relatively smooth, hard surfaces (e.g., solid plastic surfaces) and which can easily be erased from said smooth, hard surfaces by merely wiping with a dry cloth or paper tissue.
Often, the substantially non-porous substrate is a whiteboard or glass substrate, and the dry eraser material, which is typically a piece of cloth or felt material, is mounted along the bottom of a base member having the size and shape of a conventional chalkboard eraser. Typically, a cap is removably mounted on the marking end of the marker to prevent the marker from drying-out.
Although markers of the type described above have proven to be generally adequate to enable people to make erasable markings on substantially non-porous substrates, the present inventor has observed that, in practice, many people use their fingers, instead of the above-described eraser, when they wish to erase only small areas or portions of such markings made on the above-described non-porous substrates. This practice of using one's fingers, which often undesirably results in a smearing of markings on the substrate and in a dirtying of the fingers used, is usually due to the inaccessibility of the eraser (which may become lost or separated from the substrate) and/or due to the fact that the eraser is often too big and bulky to make fine erasures.
In commonly-assigned PCT Application No. PCT/US93/10231, which was published May 11, 1994, and which is incorporated herein by reference, there is disclosed an erasable writing medium composition suitable for use in porous tip pens and roller-ball pens. Said erasable writing medium composition can be used to make markings on ordinary stationery-type paper that are erasable using an elastomeric eraser of the type typically found on the end of an ordinary pencil. The present assignee has sold capillary feed markers containing the ink of the aforementioned PCT application under the trademark OUTER LIMITS.TM. ERASERHEAD.TM. erasable marker. Said marker has been sold together with a cap that is removably mounted on the writing (or front) end of the marker and which also can be removably mounted on the rear end of the marker (for example, when the marker is being used), said cap having an elastomeric eraser removably mounted within its front end and projecting out therefrom.
Also of interest to the present invention is U.S. Pat. No. 4,940,628, inventors Lin et al., which issued Jul. 10, 1990, and which is incorporated herein by reference.